EFFECTS OF BACILLUS-THURINGIENSIS VAR SAN-DIEGO ON PREDATION EFFECTIVENESS, DEVELOPMENT AND MORTALITY OF COLEOMEGILLA-MACULATA LENGI (COL, COCCINELLIDAE) LARVAE

Laboratory experiments were conducted to determine the effects of M-One(TM) (Bacillus thuringiensis var. san diego) on larval instars of Coleomegilla maculata lengi Timberlake. Coccinellid larval development (from egg hatch to adult), completed on pollen treated with suspensions of M-One(TM) at 20 ml/litre (5.6 x 10(8) CPBIU/litre) and 200 ml/litre, took respectively 29.3 and 38.5 days compared with 21.9 days for the control (water). M-One(TM) did not cause larval mortality. C. maculata third instars did not show any preference between eggs of Leptinotarsa decemlineata (Say) treated with water or with M-One(TM) at 20 ml/litre. However, at 200 ml M-One(TM)/litre, the number of eggs attacked was 34.7 % lower than the eggs treated with water only, 48 h after the beginning of the test. These results indicate that the use of M-One(TM), at the manufacturer's recommended field rate of 20 ml/litre, does not cause a major threat to larval C. maculata populations.